Anti-counterfeiting medium

Abstract

To provide forgery prevention medium which does not impair a changing effect even when a protective layer is provided on an image having the changing effect, and can generate the changing effect without the influence such as deviation of an optical path.SOLUTION: A blazed grating 3 having a serrated cross section is formed on at least a part of a base material 2, and a pattern for forming a first image and a pattern for forming a second image are formed on a serrated surface 4 facing a first direction of the brazed grating and a serrated surface 5 facing a second direction of the brazed grating, respectively.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a medium that requires an anti-counterfeiting effect, and particularly to an anti-counterfeiting medium having a latent image effect in which an image changes under visible light.

Background Art

[0002] As anti-counterfeiting technologies applied to passports and ID cards, there are an image change effect in which a plurality of images are switched and a video effect in which an image appears to move. In recent years, for the purpose of preventing forgery, variable information may be combined with a security medium having a changing effect or a video effect. As a technology for combining the change effect and variable information to improve security, a known technology of applying a lenticular lens is used. A lens-shaped lens is formed on a substrate that develops color when irradiated with laser light, and variable information is printed on the substrate with laser light later. For example, when viewed from different viewpoints A and B in FIG. 7, different patterns such as characters with personal information written on them and a face photo appear alternately, and a changing effect is obtained (Patent Document 1).

[0003] Alternatively, a printing pattern having a special optical effect such as light and dark flip-flop property or color flip-flop property is provided on a substrate, and a lens-shaped lens is laminated on the printing pattern to provide a changing effect in which different image patterns can be seen depending on the viewing angle of the medium, thereby enhancing the security (Patent Document 2).

[0004] On the one hand, when issuing a security medium such as an ID card or a passport, after imparting personal information using a laser printer, a thermal transfer printer, or the like, a colorless and transparent protective layer may be provided, for example, by providing a hologram layer at the end. However, when a lenticular lens is adopted to impart a changing effect as a security technology to these media, as shown in FIG. 8, when a protective layer such as a hologram film is overlaid on the lenticular lens, the optical path is displaced. For example, an image that should be visible from viewpoint B becomes visible from viewpoint A, and the changing effect of an image or the like provided on the base material is impaired. As a countermeasure, a device or process for not providing a protective layer only on the lenticular lens is required, resulting in an increase in cost and an increase in the number of processes.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] An object of the present invention is to provide a forgery-proof medium that can generate a changing effect without impairing the changing effect even when a protective layer is provided on an image having a changing effect and without being affected by displacement of the optical path.

Means for Solving the Problems

[0007] To solve the above problems, the present invention At least a part of a base material has a cross-section Symmetric A blazed grating having a sawtooth shape is formed, and a pattern for forming a first image on a sawtooth surface facing a first direction and a pattern for forming a second image on a sawtooth surface facing a second direction are respectively formed. The forgery-proof medium is characterized by this.

[0008] The anti-counterfeiting medium may have a blazed grating that is light-transmissive.

[0009] The anti-counterfeiting medium may be one in which the pattern forming the first image and the pattern forming the second image are formed by ink transferred from a thermal transfer ribbon.

[0010] The anti-counterfeiting medium may be one in which a light-transmissive protective layer is further laminated on the blazed grating and the pattern.

Advantages of the Invention

[0011] According to the present invention, in a medium that requires security such as an ID card or a passport, an anti-counterfeiting medium having an image with a suitable changing effect can be easily obtained, and even when a protective layer is provided in a subsequent process, the changing effect is not impaired due to a change in the optical path or the like, and an anti-counterfeiting medium that enables simplification of processing and cost reduction can be obtained.

Brief Description of the Drawings

[0012]

Figure 1

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Figure 8

Best Mode for Carrying Out the Invention

[0013] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments described below. Also, in the embodiments shown below, technically preferable limitations are imposed for carrying out the invention, but these limitations are not essential requirements of the present invention.

[0014] FIG. 1 is a schematic cross-sectional view of a portion where a blazed grating of the anti-counterfeiting medium of the present invention is formed, showing a state before a pattern of a changing image is recorded. An anti-counterfeiting medium 1 has a blazed grating 3 with a sawtooth cross-section formed on at least a part of a base material 2. The base material 2 is not particularly limited as long as it is a material having appropriate strength, durability, and processability as a medium. For example, a polycarbonate resin is preferably used. However, as long as it does not affect the formation of the blazed grating 3 described later, paper, synthetic paper, polyethylene terephthalate resin (thermoplastic PET), polyvinyl chloride resin, thermosetting polyester resin, polymethacrylic resin, and synthetic resins such as polystyrene resin may also be used.

[0015] The blazed grating 3 formed on the base material 2 can be formed, for example, by applying a resin such as a thermoplastic resin, a thermosetting resin, and an ultraviolet curable resin or an electron beam curable resin (hereinafter, also collectively referred to as a photocurable resin) to the base material, pressing a mold having irregularities to transfer the irregularities to the surface of the resin, and then curing this resin.

[0016] Examples of the thermoplastic resin include polyethylene terephthalate, polyethylene naphthalate, polycarbonate, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, nitrocellulose, polyethylene, polypropylene, acrylonitrile styrene copolymer, vinyl chloride, and polymethyl methacrylate.

[0017] Examples of the thermosetting resin include polyimide, polyamide, polyester urethane, acrylic urethane, epoxy urethane, silicone, epoxy and melamine resins.

[0018] The photocurable resin refers to a resin that cures by irradiation with light such as ultraviolet rays and electron beams. Representative resins that undergo radical polymerization upon irradiation with light include acrylic resins having an acryloyl group in the molecule. Examples thereof include epoxy acrylate-based, urethane acrylate-based, polyester acrylate-based or polyol acrylate-based oligomers or polymers, monofunctional, difunctional or polyfunctional polymerizable (meth)acrylic monomers (for example, tetrahydrofurfuryl acrylate, 2-hydroxyethyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, polyethylene glycol diacrylate, polypropylene glycol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate or pentaerythritol tetraacrylate) or their oligomers or polymers, or mixtures thereof are used.

[0019] The above-mentioned thermoplastic resin, thermosetting resin, and photocurable resin may be light-transmissive.

[0020] After performing the embossing process described above, an ink pattern is formed such that an image A, which is a first image, appears on the sawtooth surface 4 facing the first direction, that is, the surface at the angle visible from the viewpoint A, and an image B, which is a second image, appears on the sawtooth surface 5 facing the second direction, that is, the surface at the angle visible from the viewpoint B, with respect to the sawtooth-shaped peaks of the blazed grating (FIG. 2).

[0021] As a method of forming an ink pattern, for example, it can be formed by transferring the pattern of the thermal transfer ink on a thermal transfer ribbon. As the thermal transfer ribbon to be used, a known one can be appropriately selected and used. However, in order to enhance the visibility of the image, the color of the thermal transfer ink on the thermal transfer ribbon is preferably a dark color such as black. Also, images A and B are not particularly limited, but may include individual information such as face photos, names, character data such as ID numbers, etc.

[0022] As a method of forming the image pattern with the thermal transfer ink of the thermal transfer ribbon on the sawtooth surface 4 facing the first direction and the sawtooth surface 5 facing the second direction, specifically, in addition to thermal transfer using a high-definition thermal head with the thermal transfer ink of the thermal transfer ribbon, it is also possible to perform a higher-definition laser thermal transfer using laser light. Further, an indirect thermal transfer method can also be adopted in which the image patterns of image A and image B are once transferred from the thermal transfer ribbon to an intermediate transfer medium by thermal head or laser thermal transfer, and then thermally transferred again with a thermal roller or the like on the blazed grating.

[0023] The above-described recording method of transferring the thermal transfer ink from the thermal transfer ribbon is common to the method of recording a normal visual image on a medium such as a card or a booklet, and since no special process is required, it is possible to efficiently and inexpensively form a changing image.

[0024] In addition to this, known image forming technologies such as inkjet printing, laser printing technology, screen printing technology, hot stamp transfer, and photolithography technology may be appropriately selected and adopted, but it is preferable to select those suitable for recording individual information.

[0025] The image obtained by observing the anti-counterfeiting medium 1 thus is shown in Fig. 3. From viewpoint A, an image A formed by the ink pattern on the sawtooth surface 4 facing the first direction can be seen, and from viewpoint B, an image B formed by the ink pattern on the sawtooth surface 5 facing the second direction can be seen, thus obtaining a changing effect. Further, even when the optical path changes when a colorless and transparent protective layer 6 is provided as shown in Fig. 4, what can be seen is the image on the same sawtooth surface, and the images on the sawtooth surfaces facing different directions cannot be seen and, for example, the image from viewpoint A to viewpoint B cannot be seen, and a medium that does not inhibit the changing effect can be obtained.

[0026] The protective layer 6 is a substantially transparent layer so that each image on the surface of the anti-counterfeiting medium 1 on the lower layer side can be visually recognized. However, as long as the visibility is not impaired, for example, a transparent hologram layer, a printing layer, a vapor deposition layer, a barrier layer, etc. may be included, and an ultraviolet absorber, an infrared absorber, and other various additives may be included. Further, the protective layer 6 may be provided by known methods such as transfer, printing, coating, etc. after forming each image on the surface of the anti-counterfeiting medium 1 including the image on the blazed grating 3, or may be formed by being transferred simultaneously with transferring each image from an intermediate transfer medium by an indirect thermal transfer method.

[0027] Fig. 5(a) is a schematic diagram showing one form of the anti-counterfeiting medium provided with the changing image of the present invention, and is an example in the form of a card 7. The card 7 is, for example, an ID card, and a face photo, a name, and other individual information are recorded. A blazed grating is formed in a part of the surface of the card 7, in this example, in the region S in the lower right part, and an image A and an image B that become the changing image are recorded. The image A is a face photo here, and the image B is characters indicating the date of birth. When the card 7 is viewed from its normal direction, the image A and the image B overlap and both can be seen.

[0028] In this example, the blazed grating is formed such that the serrated pattern extends horizontally in the figure of Card 7. Therefore, when Images A and B are enlarged and viewed from the normal direction, as shown in Fig. 5(b), Image A is formed only on the part corresponding to the serrated surface A, and Image B is formed only on the part corresponding to the serrated surface B, resulting in a linear pattern extending horizontally. Also, as shown in the partial enlarged view of Fig. 5(c), the linear patterns of Images A and B are formed in an alternating positional relationship. Note that the direction in which the serrated pattern is formed is not limited to the horizontal direction of the figure and may be formed to extend in the vertical direction or an oblique direction.

[0029] Fig. 6 is an external view for explaining the changing effect in Card 7 of Fig. 5 and is an image diagram when Card 7 is tilted in the vertical direction. For example, when Card 7 is tilted at an angle as seen from Viewpoint A, only Image A can be seen in Region S. Conversely, when tilted at an angle as seen from Viewpoint B, only Image B can be seen in Region S. In this way, the changing effect is manifested. If the direction in which the serrated pattern is formed is the vertical direction of the figure, a similar changing effect will be manifested when Card 7 is tilted in the horizontal direction.

Explanation of Reference Numerals

[0030] 1 ··· Anti-counterfeiting medium 2 ··· Substrate 3 ··· Blazed grating 4 ··· Serrated surface facing the first direction 5 ··· Serrated surface facing the second direction 6 ··· Protective layer 7 ··· Anti-counterfeiting medium (card)

Claims

1. A forged-proof medium, wherein a serrated grating with a symmetric cross-section is formed on at least a part of a base material, and a pattern for forming a first image is formed on a serrated surface facing a first direction, and a pattern for forming a second image is formed on a serrated surface facing a second direction, respectively.

2. The forged-proof medium according to Claim 1, wherein the serrated grating is light-transmissive.

3. The forged-proof medium according to Claim 1 or 2, wherein the pattern for forming the first image and the pattern for forming the second image are formed by ink transferred from a thermal transfer ribbon.

4. The forged-proof medium according to any one of Claims 1 to 3, wherein a light-transmissive protective layer is further laminated on the serrated grating and the pattern.

Images